As known, connecting elements of the pre-cited type enable the realization of an assembled unit consisting, for instance, of a cam follower in the form of a finger lever, and a support element. Such an assembled unit minimizes the risk of a possible faulty mounting by the customer. One such error could consist in that the finger lever is mounted wrongly turned through 180° in the valve train. In this case, the contacting members, spherical head of the support element and concave depression of the finger lever, as also valve stem end and mating counter surface on the finger lever, are mistakenly exchanged. Such a faulty mounting would lead at least to a malfunction of the valve train, and, in the worst case, even to a serious damage to the engine. Further requirements made of such a connecting element are that, on the one hand, a separation of the finger lever and the support element due to transport conditions is reliably excluded and the connecting element, on the other hand, makes no negative contribution to the valve train friction during the pivoting motion of the finger lever on the support element.
DE 102 49 560 A1 proposes a connecting element that advantageously meets the aforesaid requirements. In the case of this connecting element that is made of flat material, the spherical end of the support element is clipped behind an oval recess of the connecting element, which recess is situated under the concave depression of the finger lever. In this way, the connecting element does indeed engage into the annular groove under the spherical end but it still permits a minimum-friction pivoting movement in activation direction of the gas exchange valve. A pre-condition for a perfect clipping-in of the support element behind the connecting element, however, is an elastic deformation of the latter in the region of the recess. The required elasticity can be achieved without any problem with a suitable geometry of the recess and suitable properties and thickness of the connecting element material, but a mounting gap still subsists crosswise to the activating direction of the finger lever between the connecting element and the annular groove in the support element. Consequently, a pivoting movement of the finger lever crosswise to its activating direction is also not completely impeded by the connecting element, and this pivoting movement can then have a range of up to 15°. Such a tilting of the finger lever about its longitudinal axis can likewise occur in the assembled engine, viz., upon loss of contact between the finger lever and the activating cam. Reasons for such a loss of contact can be an undesired sinking of the mostly used support elements equipped with hydraulic valve lash adjustment or a migration of the finger lever away from the activating cam due to an excessive speed of rotation of the internal combustion engine.
In this connection, special attention must be paid to finger levers with very narrow cam contacting surfaces. Such finger levers are used with multi-valve engines installed in a confined design space or also in variable valve controls in which a set of cams consisting of several cams of different lifts is mounted for axial displacement on a camshaft and one of these cams suited to the operating state of the engine has to be brought into engagement with the finger lever. In such an arrangement, there is a great danger of the finger lever tilting further away from or completely off the support element because, for a renewed contact with its cam, the finger lever can no longer align itself adequately with the cam due to the narrow cam contacting surface.